Cable gripper insert

ABSTRACT

Cable gripper jaws and cable gripper jaw members having at least one removable, cable gripping surface insert. The gripper jaw member has a recess for receiving the insert and the insert can engage with the gripper member by means of a fixative and/or a mechanical engaging means, including mechanical interlocking means. The insert and gripper member can be of different materials, including metals of differing hardness ratings. The cable gripper jaws have utility in the cable gripping fields, including in the drilling and horizontal directional drilling industries, and as part of a method for pulling cable through space, including pulling cable through space in the pipe bursting and trenchless pipe replacement industries.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. patent application Ser. No.15/681,048, filed Aug. 18, 2017, which claims the benefit of ProvisionalApplication No. 62/377,492, filed Aug. 19, 2016, the disclosures ofwhich are hereby expressly incorporated in their entirety by referenceherein.

FIELD OF USE

Embodiments of the present disclosure find applicability in the field ofcable clamping and cable gripping mechanisms for gripping cable beingpulled through space. Useful industries that use cable grippingmechanisms are the drilling industries, including the vertical andhorizontal directional drilling industries; the cable and conduit layingindustries; towing industries, and other industries where cable ispulled through space above or below ground, including the pipe burstingand trenchless pipe replacement industries.

BACKGROUND

It is common practice in fields and industries that require pullingmetal cable through space to use a cable gripping mechanism. One common,useful mechanism includes using a gripper having metal “teeth” to bitethe cable and hold it in position. These metal grippers or “jaws”typically are manufactured as a single, integral unit, generally from aferrous metal such as steel, that is both soft enough to absorb andsustain the load that cable pulling requires, and hard enough that thecable gripping surface, typically textured in some way to provide theteeth, can bite into and hold the cable.

One exemplary industry that uses cable gripping “jaws” is the horizontaldirectional drilling industry. Here, cable is pulled through space usingthrust and pull back forces in the range of at least about 5,000-100,000lbs. Vertical drilling systems can use even greater force. Otherindustries include towing industries, particularly those that tow heavyitems, including vehicles, boats, ships, and the like. Still otherindustries are those that lay large conduit, cable and/or pipe above orbelow ground, including the pipe bursting and trenchless pipereplacement industries.

The dual function required of a cable gripper (high load capacity andhigh hardness for cable gripping) generally requires selecting a metalthat is a compromise between the two ideals of high load capacity andhigh hardness. This need to compromise between two different metalcharacteristics can limit the overall life of the gripper. Typically, anupper limit is placed on the choice of metal hardness, driven by theload-bearing requirements of the gripper. This choice generally resultsin the cable gripping surface wearing down over time, requiring thewhole gripper to be replaced even though the rest of the gripper'sfunctions, including its load bearing capability, remain operative andfunctional. Replacing the whole gripper is both costly andtime-consuming for the consumer, and also expensive and time-consumingfor the manufacturer to fabricate.

In the field of horizontal directional drilling, for example, a standardmetal commonly used to fabricate cable grippers is E9310. E9310 is a lowalloy steel that can be hardened to a surface Rockwell hardness of up toabout 62, while maintaining a more desired, lower internal Rockwellhardness for load capacity. While functional and useful, this singlemetal has an upper limit to its surface hardness, which limits the lifeof the gripper's cable gripping surface.

There remains a need for a metal cable gripper that can have both adesired high hardness on its cable gripping surface and a desired lowerhardness on its inner, load-bearing surface without having to compromiseon metal choices, or limit the life of the gripper. There also remains aneed for a metal cable gripper having a cable gripping surface that ismore resistant to wear than the cable grippers currently in the art.

The present disclosure describes improvements in metal cable grippingmechanisms and methods of use thereof that overcome deficiencies in themechanisms and devices of the prior art.

SUMMARY

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This summary is not intended to identify key features ofthe claimed subject matter on its own, nor is it intended to be used onits own as an aid in determining the scope of the claimed subjectmatter.

In accordance with one embodiment of the disclosure, provided herein isa novel cable gripper or “jaw” having an axially concave surfacedimensioned and configured to engage a cable. The cable engaging surfacetypically is threaded, grooved, or otherwise textured to provide meansfor gripping or “biting” into the cable. In one embodiment, useful cablejaws comprise a plurality of two or more gripper members whose innercable gripping surfaces together define an axial hole dimensioned toreceive a cable.

Cable gripping mechanisms are used in a wide range of environments andaccordingly the overall shape of the gripper can vary, according to thelocation and functionality of the gripper relative to an overall cablepulling apparatus. In one embodiment, the outer surface of the cablegripper device contacts another component of a cable pulling apparatus,and its outer surface is configured to support that contact. Thus, forexample, when the gripper fits inside a substantially hollow housing andslides against the inner surface of the housing, the outer surface ofthe gripper device can have a convex shape to provide a camming surfacethat can slide against the housing's inner surface. One example ofhollow housing is a bursting head housing. U.S. Pat. No. 9,360,148 thedisclosure of which is incorporated herein by reference, provides a moredetailed description of bursting head devices. In another embodiment thedevice can have a shape and mechanical linkage means for promotingsliding along a part of the cable pulling apparatus. U.S. patentapplication Ser. No. 14/726,546, the disclosure of which is incorporatedherein by reference, provides a more detailed description of cablegripper jaws for cable pulling apparatuses.

Cable grippers of the instant disclosure differ from grippers of the artin that the gripper's cable gripping surface comprises at least oneremovable insert that sits in a recess of the gripper body or gripperbase. When in position, the insert provides the means for gripping thecable. In one embodiment, the cable gripping means of the grippers ofthis disclosure comprise a single insert. In another embodiment, thecable gripping means comprises a plurality of two or more inserts. Instill another embodiment, the insert and gripper body or base arecomposed of two different metals.

In one embodiment, the inserts are spaced along the axial length of therecess.

In another embodiment, the gripper insert has a substantially concaveupper or “inner” cable gripping surface and a lower, or “outer” gripperbase-engaging surface. In still another embodiment, the insert'sbase-engaging surface is dimensioned and configured to mirror thegripper base's recess surface.

In one embodiment, the recess in the gripper base that is dimensioned toreceive and engage the gripper insert is curved, or has a substantiallyconcave surface. In another embodiment the outer surface of the gripperinsert also is curved and has a substantially convex surface thatmirrors the gripper base recess shape.

In another embodiment the gripper base recess surface is substantiallyflat. In still another embodiment the insert engages mechanically withthe base. In one embodiment the mechanical engaging means acts as amechanical lock. In one embodiment the lock can comprise a boundariedchannel into which the insert is set. In still another embodiment, thelock can comprise a longitudinal series of boundaries or channels intowhich a plurality of inserts are set. In still another embodiment, theboundaries defining the length of the insert channels comprise dividersor steps such that the inserts sit in individual channels in the recess,separated from one another and held in position by the dividers orsteps. In still another embodiment the dividers are competent to holdthe inserts in position during the thrust and pullback actions of acable pulling operation. In still another embodiment the cable engagingsurface of the dividers also is threaded, grooved or otherwise texturedto bite the cable.

In yet another embodiment the mechanical engaging means comprises aninterlocking mechanism. In one embodiment the interlocking mechanism cancomprise a dovetail type joint. In still another embodiment themechanical interlocking mechanism can comprise a mortise and tenon typejoint. In still another embodiment the mechanical interlocking mechanismcan comprise a tongue and groove type joint.

In another embodiment the gripper device can include an insert positionretaining means. In one embodiment the position retaining means can bemechanical, including, without limitation, a pin, screw, or bolt. Inanother embodiment, the position retaining means can include anfixative, adhesive or sealant, including, without limitation, epoxy orsilicone.

In still another embodiment the gripper base can be configured to retainthe insert in position and limit longitudinal shifting of the gripperinsert during the cable pulling operation. In still another embodimentthe gripper base comprises means for absorbing the load placed on thegripper insert during cable pulling operation. In one embodiment, thegripper comprises a bracing means that acts as a back stop for theinsert during operation. Where a plurality of gripper inserts areprovided the channel dividers or insert boundaries can provide thebracing or backstop means. Where a single gripper insert is provided, ashelf or wall can provide the bracing or backstop means.

DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thisdisclosure will become more readily appreciated as the same becomebetter understood by reference to the following detailed description,when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective view of a cable gripper member comprising aplurality of gripper inserts, according to one embodiment of the presentdisclosure;

FIG. 2 is an exploded view of the cable gripper member of FIG. 1 ;

FIGS. 3A and 3B are views of cable gripper members comprising aplurality of gripper inserts according to another embodiment of thepresent disclosure, wherein 3A is an exploded view, and 3B shows threegripper members with integrated gripper inserts;

FIG. 4 is an exploded view of a cable gripper member comprising agripper insert according to another embodiment of the presentdisclosure;

FIG. 5 is a perspective view of the cable gripper member of FIG. 4 ,with the gripper insert integrated into the gripper base;

FIG. 6 is an exploded view of a cable gripper member comprising agripper insert according to another embodiment of the presentdisclosure;

FIG. 7 is a perspective view of a cable gripper member comprising agripper insert according to another embodiment of the presentdisclosure;

FIGS. 8A and 8B are views a cable gripper member comprising a gripperinsert according to another embodiment of the present disclosure, where8A is a perspective view showing the insert integrated into the gripperbase and 8B is an exploded view of the gripper member in view 8A;

FIGS. 9A and 9B are perspective views of cable gripper inserts accordingto different embodiments of the present disclosure, and

FIG. 10 is an exploded view of a cable gripper member comprising agripper insert according to another embodiment of the presentdisclosure.

DETAILED DESCRIPTION

Embodiments of the present disclosure provide devices, components,mechanisms and methods of use directed to improved means for gripping acable surface, particularly a cable to be pulled through space. Theimprovement comprises providing a removable and replaceable cablegripping surface to a cable gripping device. The removable andreplaceable gripping surface can be provided by means of an insert whichmay be made of a different material than that of the gripper base orgripper body. The insert also may be secured or otherwise engaged withthe gripper body by any suitable means. One useful means can be bymechanical means, including mechanical locking or interlocking means.Other means can include fixatives, adhesives and/or sealants. In onepreferred embodiment, the mechanical securing means can includemechanical means for engaging the insert with the gripper base,mechanical insert position retaining means, and a mechanical loadbearing brace for absorbing pulling forces on the gripper insert duringoperation.

Referring to FIGS. 1 and 2 , one embodiment of a useful cable grippingmechanism and device in accordance with the present disclosure is shown.In the figures, a cable gripper member 10 is shown. In the embodimentillustrated in FIGS. 1 and 2 the gripper member has an overall wedgeshape and the member shown comprises one half of a gripper device, theother half being a substantial mirror of the half shown. The gripperitself, comprising the two halves, also has an overall wedge shape.Gripper member 10 comprises a gripper body or gripper base 22 having anouter or lower surface 14 and inner, or upper surface 12. Upper surface12 has a cable gripping surface provided by a cable gripper insert 16.When two of the cable members shown in FIG. 1 are placed together suchthat their cable gripping surfaces face each other, the inner, cablegripping surfaces together define a hollow opening or tube dimensionedto receive a cable.

Cable gripping surface 12 comprises at least one insert 16 that sits ina recess of cable base 22. Accordingly, gripper base upper surface 12comprises means for receiving and engaging a cable gripping insert. Inthe embodiment illustrated in the figures, three inserts are shown. Aswill be appreciated by those skilled in the art, fewer inserts,including two or one, and more inserts, can be used to advantage.

Recess 20 is configured to receive and mechanically engage insert 16.Insert 16 itself comprises an outer or lower, gripper base-engagingsurface 26 dimensioned and configured to sit in recess 20, and an inneror upper, cable engaging surface 24, typically textured to enhance thesurface's ability to dig into or “bite” the cable. One common means forcreating a “biting” texture on a cable gripping surface is by forming athreaded or grooved texture on the cable gripping surface.

In the figures the gripper base insert receiving, upper surfacecomprises one or more recesses 20 dimensioned to receive the insert. Inthe figures the insert recess surface comprises a series of recesses orchannels dimensioned to receive the individual inserts. The channels,and the inserts they hold, can be separated by dividers or steps in therecess axial opening and which provide a mechanical engaging or lockingmeans for holding each insert in place. In the figures the channels 20are depicted as concave and the outer or lower surface 26 of the insertsis a mirror image thereof, namely convex. Dividers 18 can providemechanical means for holding the insert(s) in position in recess 20.Dividers 18 also can provide load bearing bracing means for absorbingpulling forces on the gripper insert during operation. The cableengaging surface of dividers 18 also can be configured to engage thecable. For example, the surfaces can be textured, e.g., grooved, to biteinto the cable they contact.

The embodiment depicted in FIG. 3 is a three-member gripper devicehaving an overall cone shape. These gripper devices have utility as partof the gripping mechanism in a bursting head cone commonly used inhorizontal directional drilling. As for the wedge-shaped gripper membersshown in FIGS. 1 and 2 , when the members of the cone-shaped gripper areput together, their inner, cable gripping surfaces together define anaxial opening or channel configured and dimensioned to receive a cable.

In FIGS. 3A and 3B channel dividers 18 that comprise the mechanicalengaging or locking means are configured as dovetails, as are thelateral edges of insert 16, such that the inserts can slide intorecesses 20 and interlock with dividers 18 as a dovetail type joint.

In FIGS. 4-10 , embodiments of gripper members 10 comprising a singleinsert 16 are illustrated. In the figures the single insert sits alongthe central, longitudinal axis of gripper base 22. In the embodimentsillustrated in FIGS. 4-7 , the mechanical engaging or locking meanscomprises a dovetail type joint that extends along the centrallongitudinal axis of the insert and the gripper base. In the case of thegripper insert, the dove tail 28 can extend down from the outer or lowersurface 26 of the insert and can mirror a dovetail channel or recess 20in upper or inner surface 12 of gripper base 22, extending along thegripper base's centrally located longitudinal axis.

Additional mechanical insert position retaining means 30 also can beused to advantage. In FIGS. 4-6 a pin, such as a compressible spring orroll pin, is depicted as providing an additional mechanical means 30 forsecuring an insert in position. Position retaining means 30 can be usedadvantageously as one means for limiting longitudinal shifting ormovement of insert 16 back along recess 20 and out from a free joint endon gripper base 22. In FIG. 7 the mechanical position retaining means 30illustrated comprises a screw means positioned at the free joint end. InFIGS. 8A and 8B the mechanical position retaining means 30 illustratedcomprises a bolting means. As will be appreciated by those havingordinary skill in the art, insert position retaining means can compriseany useful means, including a pin, bolt, screw or other affixing means.Additionally, and/or alternatively, fixatives such as, withoutlimitation, epoxy or silicone also can be used to advantage.

In FIGS. 4 and 6 mechanical position retaining means 30 fits through ahollow channel formed by a lateral gap 32 that traverses the dovetailextending down from insert 16's outer surface 26 and a correspondinglateral gap that traverses recess 20 in gripper base 22, from pinholeopening 34. When the dovetail and recess are joined, the two gapstogether form a hollow channel into which the pin can be inserted andengaged. As will be appreciated by those having ordinary skill in theart, a fabricator can adjust the depth of the dovetail as desired andallowed by size constraints, utilize larger or smaller mechanicalposition retaining means 30, and position them at different locations,including positions such that retaining means 30 occurs entirely withineach dovetail. In FIG. 7 , for example, mechanical position retainingmeans 30 occurs at the free end of a dove tail type joint located at theposterior or back end of the gripper base.

As will be appreciated by those having ordinary skill in the art, a widevariation and range of mechanical engaging and/or locking means areavailable and can be fabricated without undue experimentation. A similarrange of options exist for mechanical position retaining means. Theactual selection made by a fabricator will depend on standardcalculations and decisions made that include, without limitation, thesize and number of inserts to be used, the desired dimensions of theinsert and gripper base, the location and function of the gripper in thecable pulling apparatus, the type of materials selected for both thebase and the inserts, and the pull and thrust forces the gripper baseand inserts will experience.

For example, FIGS. 8A and 8B illustrate yet another exemplary embodimentwhere the mechanical engaging means comprises a mortise and tenon typejoint, together with a laterally located mechanical position retainingmeans. Other useful exemplary mechanical engaging or lock means includetongue and groove type joints. FIG. 10 illustrates still anotherexemplary embodiment comprising laterally positioned sliding dovetailtype joints that traverse the width of insert 16 and gripper base 22.FIGS. 9A and 9B illustrate still other exemplary gripper insertembodiments where the mechanical locking means comprises a pair ofparallel, opposing dovetails (FIG. 9A), or joint tongues (FIG. 9B) thatextend out from the sides of insert 16. These parallel, opposingextensions 28 on insert 16 join corresponding parallel, opposingchannels in the walls of the gripper base recess, the channelsdimensioned to mirror and receive insert 16's parallel, opposingextensions.

As will be appreciated by those of ordinary skill in the art, where thecable gripping surface of a gripper member comprises a removable insert,the cable pulling force, which can exert pressures anywhere in the rangeof least about 5,000-100,000 lbs, will pull on the insert itself.Accordingly, bracing means for absorbing and translating the pressurefrom the inset to the gripper body are advantageous to prevent movementof the insert forward along the gripper base recess during operation.Where multiple, smaller inserts are utilized as illustrated in FIGS. 1-3and 10 , dividers 18 can provide the bracing means. Where a singleinsert is utilized, for example as illustrated in FIGS. 4-9 , mechanicalbracing means can advantageously be provided by means of a shelf 40.See, for example, FIGS. 4, 6, and 8B.

The length, depth, and thickness of the mechanical bracing meansselected will depend, as above, on the size and length of the gripperbase and insert chosen, gripper function, selected component materials,and operational cable pulling pressures, among other criteria. Usingstandard calculations a fabricator can readily calculate the desireddimensions for shelf 40 to provide the desired bracing functionality.Similarly, as also will be appreciated by those having ordinary skill inthe art, corner joint 46 between shelf wall 42 and shelf floor 44 (see,for example, FIGS. 4, 6, and 8B) can comprise a possible stress pointwhen absorbing cable pulling pressures. Accordingly, the choice of angleradius selected for joint 46 can depend on the available thickness ofgripper base lower surface 14, particularly in the vicinity of joint 46.Where a gripper base has sufficient thickness and load bearing capacityto absorb operational cable pulling pressures, shelf joint 46 cancomprise a substantially 90° angle (see, for example, FIGS. 5 and 8B).For thinner gripper bases, a shelf joint 46 preferably can be calculatedas a radius to prevent unwanted deforming, bending or flexing at thatpoint (see, for example, FIG. 4 ). The desired radius can be calculatedreadily using standard stress analysis calculations, taking intoaccount, for example, metal hardness, gripper dimensions and operationalpressures.

It will be appreciated by those having ordinary skill in the art that,provided with this disclosure, means now are provided for fabricatingcable gripper jaws of multiple, different metals. In particular, it nowis available to the fabricator to select a metal of a desired hardnessfor enhanced or preferred cable gripping capability, withoutcompromising the load bearing requirements of the gripper body or base.For example, in the field of horizontal directional drilling, includingthe pipe bursting and trenches pipe replacement industries, usefulinsert metals can include metals having a Rockwell rating greater than62. Carbide steel, for example, may be used to advantage. Similarly,gripper bodies now can be fabricated of a metal having enhanced loadbearing capacity. Such metals may have a Rockwell hardness rating of 41or below. In addition, gripper body metals can now be selected inaddition to E9310, and a greater range of metal curing or heattreatments now are available, including through hardening, if desired,as compared with case hardened steel. By selecting individual metalsthat best match the different function of the gripper body or base andthe gripper insert, one can fabricate a gripper jaw of enhancedintegrity, longevity and stability. Moreover, by providing means forreplacing the cable gripping mechanism or means of a gripper jaw orgripper jaw component or member, the longevity of the gripper isenhanced and conserved because only the insert needs to be replaced inthe event the gripping means or teeth become worn.

Installation and replacement of the insert is simple. Where themechanical engaging means comprises a joint, including, for example adovetail type joint, the insert can be readily slid into and out of thegripper base by engaging or disengaging the joining components of theinsert and gripper base. Once the insert is engaged with the gripperbase and in position, any position retaining means can be inserted, forexample, by means of a hammer, punch, screwdriver or other standardmeans. To replace an insert, a position retaining means first can beextracted, e.g., by means of a punch, and then the insert can be slidout from the gripper base. Where the insert itself sits in a channel,for example as illustrated in FIGS. 1-3 , insert 16 can be pressed intoposition in channel recess 20. If desired, additional means can beprovided for further affixing the insert in position in the recessusing, for example, epoxy or silicone. As the gripper insert's cablegripping surface gets worn down with use, the insert can be extracted orlifted from the base using, for example a punch or other standard tools,and a new insert installed in the recess.

Embodiments of this disclosure may be embodied in other specific formswithout departing from the spirit or essential characteristics thereof.The present embodiments are therefore to be considered in all respectsas illustrative and not restrictive, the scope of the disclosure beingindicated by the appended claims rather than by the foregoingdescription, and all changes that come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.While illustrative embodiments have been illustrated and described, itwill be appreciated that various changes can be made therein withoutdeparting from the spirit and scope of the disclosure.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A cable grippercomponent comprising: a gripper base having an upper surface and anopposing lower surface along said gripper base longitudinal axis, saidgripper base upper surface comprising a channel extending along a lengthof said gripper base longitudinal axis; a gripper insert having atextured, concave, cable engaging upper surface and an opposing lowersurface along said gripper insert longitudinal axis, said opposing lowersurface dimensioned to mirror and removably engage with said gripperbase channel, and means for mechanically coupling said insert to saidbase channel such that when said gripper insert lower surface is engagedin said gripper base upper surface channel, said gripper insert providesthe cable gripping surface of said gripper component.
 2. The cablegripper component of claim 1 wherein said gripper base upper surfacefurther is configured to contact at least one axial end of said gripperinsert.
 3. The cable gripper component of claim 2 wherein said gripperbase contact configuration is competent to limit longitudinal movementof said insert relative to said base.
 4. The cable gripper component ofclaim 1 wherein said gripper insert and said gripper base compositionshave different metal hardness ratings.
 5. The cable gripper component ofclaim 1 wherein said gripper base upper surface comprises a plurality ofchannels along said gripper base longitudinal axis and a plurality ofsaid gripper inserts, each said insert having a lower surfacedimensioned to mirror and removably engage with said gripper basechannels.
 6. A cable gripper insert for use in a cable gripper jaw, theinsert having a textured, concave, cable engaging upper surface and anopposing lower surface along said gripper insert longitudinal axis, saidopposing lower surface comprising a tail extending out from said lowersurface and along said longitudinal axis and dimensioned to mirror andremovably engage with a channel in a gripper base such that when saidgripper insert lower surface tail is engaged in said gripper basechannel, said gripper insert provides the cable gripping surface of saidcable gripper jaw.
 7. The cable gripper insert of claim 6 wherein thecomposition of said insert comprises carbide steel.